In the past in the case of a broad pay zone or multi pay zone to be completed the procedure was to break it into sections. The fracturing and gravel packing equipment is run into cased and perforated hole along with an isolation packer. The packer would be set to isolate the lowermost zone and the isolated zone would then be fractured below that packer. Thereafter, gravel would be delivered outside screens through a crossover to fill the annular space around the screen with gravel. After that the packer would remain in the zone just gravel packed along with the screens with gravel on their exterior as the crossover and associated wash pipe were pulled out through the already set packer. After that zone was isolated, fractured, and gravel packed another trip in the hole with a similar assembly as used for the lowest zone would be run in for doing the same for the next zone up. This process continued until all zones or sections of a continuous zone were completed.
This technique required many trips in and out of the wellbore and that translated into very high expenses for rig time. One of the reasons that this staged procedure was used was that to do it another way where an entire interval could be isolated and fractured and gravel packed at once required packers to then be set in the annulus after gravel packing. The packers that had been available were not known for reliable sealing against the inside wall of casing if the annular space was full of gravel.
More recently packer designs have evolved and sealing in an annulus that is full of gravel is possible. An example of such a packer is U.S. Pat. No. 6,896,049. Other packer designs are illustrated in U.S. Pat. Nos. 6,782,946; 5,988,276; 6,009,951; 7,100,690; 5,184,677 and 6,513,600.
The present method involves the use of packers that can reliably seal against casing in an annulus filled with gravel so that in one trip an entire interval or discrete pay zones can be isolated at once and fractured and then gravel packed and then packers that are already in place to either split up one zone or to isolate spaced zones can be set where gravel is present in the annular space. This allows these three procedures to be done in one trip for multiple zones or discrete segments of a single zone and still allow reliable isolation between zones or segments to occur with packers that can get a seal in a gravel environment. Different packer designs are contemplated for this service. These and other aspects of the present invention will be more readily apparent from a review of the description of the preferred embodiment and the associated drawings while recognizing that the claims determine the full scope of the invention.